The invention relates to an apparatus for conveying printed products and a system provided with such an apparatus.
Conveyors have been generally disclosed in the art. An accumulating section of a conveyor can be provided, for example, with a belt or rollers on which the printed products are conveyed from the intake area to the discharge area. Such conveyors are used during the production of printed products, for example to convey book blocks. With the digital book production, paper webs or individual sheets are imprinted by a digital printing press and book blocks are thus produced which are provided with a cover during a further processing step, for example in a perfect binder. Interlinked digital book production systems, such as the one described in European patent document No. 08405266.1, permit a high output. Books may thus be produced in series with a large number of copies as well as in series with a small number of copies.
However, if a system of this type must be shut down, for example due to a malfunction in a perfect binder, this not only results in a loss of time, but also causes a high amount of waste material.
Short-time interruptions can be compensated for by the conveyor by correspondingly adapting the speed or by allowing the printed products to accumulate one behind the other such that the spacing is reduced to “zero” and the printed products will touch each other. The conveyor can thus form a buffer zone during an interruption, but only for a limited number of products.
Conveyors with accumulating sections are disclosed in the art where the printed products are accumulated to contact each other. Transport systems with slip are used for this, where these systems reduce the transporting effect during the accumulation. However, the clocking rates and buffer locations for these systems are limited. Also disclosed are so-called spiral towers of which two are generally arranged in series. Spiral towers of this type always comprise a plurality of windings in which the printed products can be stored temporarily with the aid of diverters. In the process, a direct connection is created between two processing operations. If a malfunction occurs in the following machine, the diverters arranged in the conveyor redirect the product flow to a first spiral tower which conveys the products, for example, in upward direction. A second spiral tower can be connected in series and can then convey the printed products once more in downward direction. As a result of the spiral arrangement of the transporting system, it is possible to temporarily store a relatively high number of printed products until the capacity limit is reached. However, during the re-introduction of the printed products into the conveyor with the aid of the diverters, the sequence of the printed products is changed. In addition, such spiral towers require a relatively large amount of space and have a comparatively involved construction.